Per discussion, implement the Omaha Client Update Protocol (CUP) in src/crypto.

google_apis/cup/client_update_protocol_openssl.cc

Index: google_apis/cup/client_update_protocol_openssl.cc
===================================================================
--- google_apis/cup/client_update_protocol_openssl.cc	(revision 0)
+++ google_apis/cup/client_update_protocol_openssl.cc	(revision 0)
@@ -0,0 +1,58 @@
+
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "google_apis/cup/client_update_protocol.h"
+
+#include "base/logging.h"
+
+class OpenSSLCupKeyImpl : public ClientUpdateProtocol::CupKeyImpl {
+ public:
+  OpenSSLCupKeyImpl();
+  virtual ~OpenSSLCupKeyImpl();
+
+  virtual size_t PublicKeyLength() const OVERRIDE;
+  virtual std::vector<uint8> EncryptKeySource(
+      const std::vector<uint8>& key_source) OVERRIDE;
+
+  bool LoadPublicKey(const base::StringPiece& public_key);
+};
+
+OpenSSLCupKeyImpl::OpenSSLCupKeyImpl() {
+  NOTIMPLEMENTED();
+}
+
+OpenSSLCupKeyImpl::~OpenSSLCupKeyImpl() {
+  NOTIMPLEMENTED();
+}
+
+bool OpenSSLCupKeyImpl::LoadPublicKey(
+    const base::StringPiece& public_key) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+size_t OpenSSLCupKeyImpl::PublicKeyLength() const {
+  NOTIMPLEMENTED();
+  return 0;
+}
+
+std::vector<uint8> OpenSSLCupKeyImpl::EncryptKeySource(
+    const std::vector<uint8>& key_source) {
+  NOTIMPLEMENTED();
+  return std::vector<uint8>();
+}
+
+ClientUpdateProtocol::CupKeyImpl* ClientUpdateProtocol::GetCupKeyImpl(
+      const base::StringPiece& public_key) {
+  scoped_ptr<OpenSSLCupKeyImpl> result(new OpenSSLCupKeyImpl());
+  if (!result.get())
+    return NULL;
+
+  if (!result->LoadPublicKey(public_key))
+    return NULL;
+
+  return result.release();
+}
+